1. Field of the Invention
The present invention relates to an image-processing device and an image-processing method, and particularly to an image-processing device and an image-processing method for superimposing high-resolution character data on low-resolution image data.
2. Related Art
Various image-processing devices and image-processing methods for superimposing high-resolution character data on low-resolution image data have been proposed. One such conventional image-processing device includes inputting means for inputting original image data of a prescribed resolution; determining means for determining whether the original image data inputted by the inputting means is character data or photographic data; character data generating means for generating binary character data based on data determined to be character data; photographic data generating means for generating multi-value photographic data with a resolution lower than the prescribed resolution, based on data determined to be photographic data; synthesizing means for synthesizing and developing the character data generated by the character data generating means and the photographic data generated by the photographic data generating means; and outputting means for outputting the image data synthesized and developed by the synthesizing means (Japanese Patent-Application Publication No. HEI-8-139904).
When original image data of a prescribed resolution is inputted into an image-processing device having this construction, the image-processing device determines whether the inputted image data is character data or photographic data. The image-processing device generates binary character data based on data determined to be character data and multi-value photographic data of a resolution lower than the prescribed resolution based on data determined to be photographic data. The image-processing device synthesizes and develops the character data generated by the character data generating means and the photographic data generated by the photographic data generating means and outputs the synthesized image data.
Hence, the image-processing device can reduce the amount of data in the entire image by binarizeing character data and processing photographic data as multi-value photographic data with low resolution. The image-processing device can also reduce the amount of time required for processing character data and thus the amount of time for processing the overall synthesized image. Further, the character portion of the image can be reproduced satisfactorily. It is also possible to reduce the time required to process the overall image data by performing a binarization process on the character portion of the image and by performing a process to reduce the resolution in the photographic portion of the image.
However, when all or part of the high-resolution character data is placed over low-resolution photographic data in the conventional image-processing device described above, the portion of character data placed over the photographic data is processed as low-resolution photographic data. Hence, the portion of the character drawn over the photograph is printed in a lower quality and, hence, suffers in appearance.